xdiff/xmerge.c

   1 /*
   2  *  LibXDiff by Davide Libenzi ( File Differential Library )
   3  *  Copyright (C) 2003-2006 Davide Libenzi, Johannes E. Schindelin
   4  *
   5  *  This library is free software; you can redistribute it and/or
   6  *  modify it under the terms of the GNU Lesser General Public
   7  *  License as published by the Free Software Foundation; either
   8  *  version 2.1 of the License, or (at your option) any later version.
   9  *
  10  *  This library is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  *  Lesser General Public License for more details.
  14  *
  15  *  You should have received a copy of the GNU Lesser General Public
  16  *  License along with this library; if not, write to the Free Software
  17  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  18  *
  19  *  Davide Libenzi <davidel@xmailserver.org>
  20  *
  21  */
  22
  23 #include "xinclude.h"
  24
  25 typedef struct s_xdmerge {
  26         struct s_xdmerge *next;
  27         /*
  28          * 0 = conflict,
  29          * 1 = no conflict, take first,
  30          * 2 = no conflict, take second.
  31          * 3 = no conflict, take both.
  32          */
  33         int mode;
  34         /*
  35          * These point at the respective postimages.  E.g. <i1,chg1> is
  36          * how side #1 wants to change the common ancestor; if there is no
  37          * overlap, lines before i1 in the postimage of side #1 appear
  38          * in the merge result as a region touched by neither side.
  39          */
  40         long i1, i2;
  41         long chg1, chg2;
  42         /*
  43          * These point at the preimage; of course there is just one
  44          * preimage, that is from the shared common ancestor.
  45          */
  46         long i0;
  47         long chg0;
  48 } xdmerge_t;
  49
  50 static int xdl_append_merge(xdmerge_t **merge, int mode,
  51                             long i0, long chg0,
  52                             long i1, long chg1,
  53                             long i2, long chg2)
  54 {
  55         xdmerge_t *m = *merge;
  56         if (m && (i1 <= m->i1 + m->chg1 || i2 <= m->i2 + m->chg2)) {
  57                 if (mode != m->mode)
  58                         m->mode = 0;
  59                 m->chg0 = i0 + chg0 - m->i0;
  60                 m->chg1 = i1 + chg1 - m->i1;
  61                 m->chg2 = i2 + chg2 - m->i2;
  62         } else {
  63                 m = xdl_malloc(sizeof(xdmerge_t));
  64                 if (!m)
  65                         return -1;
  66                 m->next = NULL;
  67                 m->mode = mode;
  68                 m->i0 = i0;
  69                 m->chg0 = chg0;
  70                 m->i1 = i1;
  71                 m->chg1 = chg1;
  72                 m->i2 = i2;
  73                 m->chg2 = chg2;
  74                 if (*merge)
  75                         (*merge)->next = m;
  76                 *merge = m;
  77         }
  78         return 0;
  79 }
  80
  81 static int xdl_cleanup_merge(xdmerge_t *c)
  82 {
  83         int count = 0;
  84         xdmerge_t *next_c;
  85
  86         /* were there conflicts? */
  87         for (; c; c = next_c) {
  88                 if (c->mode == 0)
  89                         count++;
  90                 next_c = c->next;
  91                 free(c);
  92         }
  93         return count;
  94 }
  95
  96 static int xdl_merge_cmp_lines(xdfenv_t *xe1, int i1, xdfenv_t *xe2, int i2,
  97                 int line_count, long flags)
  98 {
  99         int i;
 100         xrecord_t **rec1 = xe1->xdf2.recs + i1;
 101         xrecord_t **rec2 = xe2->xdf2.recs + i2;
 102
 103         for (i = 0; i < line_count; i++) {
 104                 int result = xdl_recmatch(rec1[i]->ptr, rec1[i]->size,
 105                         rec2[i]->ptr, rec2[i]->size, flags);
 106                 if (!result)
 107                         return -1;
 108         }
 109         return 0;
 110 }
 111
 112 static int xdl_recs_copy_0(int use_orig, xdfenv_t *xe, int i, int count, int add_nl, char *dest)
 113 {
 114         xrecord_t **recs;
 115         int size = 0;
 116
 117         recs = (use_orig ? xe->xdf1.recs : xe->xdf2.recs) + i;
 118
 119         if (count < 1)
 120                 return 0;
 121
 122         for (i = 0; i < count; size += recs[i++]->size)
 123                 if (dest)
 124                         memcpy(dest + size, recs[i]->ptr, recs[i]->size);
 125         if (add_nl) {
 126                 i = recs[count - 1]->size;
 127                 if (i == 0 || recs[count - 1]->ptr[i - 1] != '\n') {
 128                         if (dest)
 129                                 dest[size] = '\n';
 130                         size++;
 131                 }
 132         }
 133         return size;
 134 }
 135
 136 static int xdl_recs_copy(xdfenv_t *xe, int i, int count, int add_nl, char *dest)
 137 {
 138         return xdl_recs_copy_0(0, xe, i, count, add_nl, dest);
 139 }
 140
 141 static int xdl_orig_copy(xdfenv_t *xe, int i, int count, int add_nl, char *dest)
 142 {
 143         return xdl_recs_copy_0(1, xe, i, count, add_nl, dest);
 144 }
 145
 146 static int fill_conflict_hunk(xdfenv_t *xe1, const char *name1,
 147                               xdfenv_t *xe2, const char *name2,
 148                               const char *name3,
 149                               int size, int i, int style,
 150                               xdmerge_t *m, char *dest, int marker_size)
 151 {
 152         int marker1_size = (name1 ? strlen(name1) + 1 : 0);
 153         int marker2_size = (name2 ? strlen(name2) + 1 : 0);
 154         int marker3_size = (name3 ? strlen(name3) + 1 : 0);
 155         int j;
 156
 157         if (marker_size <= 0)
 158                 marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 159
 160         /* Before conflicting part */
 161         size += xdl_recs_copy(xe1, i, m->i1 - i, 0,
 162                               dest ? dest + size : NULL);
 163
 164         if (!dest) {
 165                 size += marker_size + 1 + marker1_size;
 166         } else {
 167                 for (j = 0; j < marker_size; j++)
 168                         dest[size++] = '<';
 169                 if (marker1_size) {
 170                         dest[size] = ' ';
 171                         memcpy(dest + size + 1, name1, marker1_size - 1);
 172                         size += marker1_size;
 173                 }
 174                 dest[size++] = '\n';
 175         }
 176
 177         /* Postimage from side #1 */
 178         size += xdl_recs_copy(xe1, m->i1, m->chg1, 1,
 179                               dest ? dest + size : NULL);
 180
 181         if (style == XDL_MERGE_DIFF3) {
 182                 /* Shared preimage */
 183                 if (!dest) {
 184                         size += marker_size + 1 + marker3_size;
 185                 } else {
 186                         for (j = 0; j < marker_size; j++)
 187                                 dest[size++] = '|';
 188                         if (marker3_size) {
 189                                 dest[size] = ' ';
 190                                 memcpy(dest + size + 1, name3, marker3_size - 1);
 191                                 size += marker3_size;
 192                         }
 193                         dest[size++] = '\n';
 194                 }
 195                 size += xdl_orig_copy(xe1, m->i0, m->chg0, 1,
 196                                       dest ? dest + size : NULL);
 197         }
 198
 199         if (!dest) {
 200                 size += marker_size + 1;
 201         } else {
 202                 for (j = 0; j < marker_size; j++)
 203                         dest[size++] = '=';
 204                 dest[size++] = '\n';
 205         }
 206
 207         /* Postimage from side #2 */
 208         size += xdl_recs_copy(xe2, m->i2, m->chg2, 1,
 209                               dest ? dest + size : NULL);
 210         if (!dest) {
 211                 size += marker_size + 1 + marker2_size;
 212         } else {
 213                 for (j = 0; j < marker_size; j++)
 214                         dest[size++] = '>';
 215                 if (marker2_size) {
 216                         dest[size] = ' ';
 217                         memcpy(dest + size + 1, name2, marker2_size - 1);
 218                         size += marker2_size;
 219                 }
 220                 dest[size++] = '\n';
 221         }
 222         return size;
 223 }
 224
 225 static int xdl_fill_merge_buffer(xdfenv_t *xe1, const char *name1,
 226                                  xdfenv_t *xe2, const char *name2,
 227                                  const char *ancestor_name,
 228                                  int favor,
 229                                  xdmerge_t *m, char *dest, int style,
 230                                  int marker_size)
 231 {
 232         int size, i;
 233
 234         for (size = i = 0; m; m = m->next) {
 235                 if (favor && !m->mode)
 236                         m->mode = favor;
 237
 238                 if (m->mode == 0)
 239                         size = fill_conflict_hunk(xe1, name1, xe2, name2,
 240                                                   ancestor_name,
 241                                                   size, i, style, m, dest,
 242                                                   marker_size);
 243                 else if (m->mode & 3) {
 244                         /* Before conflicting part */
 245                         size += xdl_recs_copy(xe1, i, m->i1 - i, 0,
 246                                               dest ? dest + size : NULL);
 247                         /* Postimage from side #1 */
 248                         if (m->mode & 1)
 249                                 size += xdl_recs_copy(xe1, m->i1, m->chg1, 1,
 250                                                       dest ? dest + size : NULL);
 251                         /* Postimage from side #2 */
 252                         if (m->mode & 2)
 253                                 size += xdl_recs_copy(xe2, m->i2, m->chg2, 1,
 254                                                       dest ? dest + size : NULL);
 255                 } else
 256                         continue;
 257                 i = m->i1 + m->chg1;
 258         }
 259         size += xdl_recs_copy(xe1, i, xe1->xdf2.nrec - i, 0,
 260                               dest ? dest + size : NULL);
 261         return size;
 262 }
 263
 264 /*
 265  * Sometimes, changes are not quite identical, but differ in only a few
 266  * lines. Try hard to show only these few lines as conflicting.
 267  */
 268 static int xdl_refine_conflicts(xdfenv_t *xe1, xdfenv_t *xe2, xdmerge_t *m,
 269                 xpparam_t const *xpp)
 270 {
 271         for (; m; m = m->next) {
 272                 mmfile_t t1, t2;
 273                 xdfenv_t xe;
 274                 xdchange_t *xscr, *x;
 275                 int i1 = m->i1, i2 = m->i2;
 276
 277                 /* let's handle just the conflicts */
 278                 if (m->mode)
 279                         continue;
 280
 281                 /* no sense refining a conflict when one side is empty */
 282                 if (m->chg1 == 0 || m->chg2 == 0)
 283                         continue;
 284
 285                 /*
 286                  * This probably does not work outside git, since
 287                  * we have a very simple mmfile structure.
 288                  */
 289                 t1.ptr = (char *)xe1->xdf2.recs[m->i1]->ptr;
 290                 t1.size = xe1->xdf2.recs[m->i1 + m->chg1 - 1]->ptr
 291                         + xe1->xdf2.recs[m->i1 + m->chg1 - 1]->size - t1.ptr;
 292                 t2.ptr = (char *)xe2->xdf2.recs[m->i2]->ptr;
 293                 t2.size = xe2->xdf2.recs[m->i2 + m->chg2 - 1]->ptr
 294                         + xe2->xdf2.recs[m->i2 + m->chg2 - 1]->size - t2.ptr;
 295                 if (xdl_do_diff(&t1, &t2, xpp, &xe) < 0)
 296                         return -1;
 297                 if (xdl_change_compact(&xe.xdf1, &xe.xdf2, xpp->flags) < 0 ||
 298                     xdl_change_compact(&xe.xdf2, &xe.xdf1, xpp->flags) < 0 ||
 299                     xdl_build_script(&xe, &xscr) < 0) {
 300                         xdl_free_env(&xe);
 301                         return -1;
 302                 }
 303                 if (!xscr) {
 304                         /* If this happens, the changes are identical. */
 305                         xdl_free_env(&xe);
 306                         m->mode = 4;
 307                         continue;
 308                 }
 309                 x = xscr;
 310                 m->i1 = xscr->i1 + i1;
 311                 m->chg1 = xscr->chg1;
 312                 m->i2 = xscr->i2 + i2;
 313                 m->chg2 = xscr->chg2;
 314                 while (xscr->next) {
 315                         xdmerge_t *m2 = xdl_malloc(sizeof(xdmerge_t));
 316                         if (!m2) {
 317                                 xdl_free_env(&xe);
 318                                 xdl_free_script(x);
 319                                 return -1;
 320                         }
 321                         xscr = xscr->next;
 322                         m2->next = m->next;
 323                         m->next = m2;
 324                         m = m2;
 325                         m->mode = 0;
 326                         m->i1 = xscr->i1 + i1;
 327                         m->chg1 = xscr->chg1;
 328                         m->i2 = xscr->i2 + i2;
 329                         m->chg2 = xscr->chg2;
 330                 }
 331                 xdl_free_env(&xe);
 332                 xdl_free_script(x);
 333         }
 334         return 0;
 335 }
 336
 337 static int line_contains_alnum(const char *ptr, long size)
 338 {
 339         while (size--)
 340                 if (isalnum(*(ptr++)))
 341                         return 1;
 342         return 0;
 343 }
 344
 345 static int lines_contain_alnum(xdfenv_t *xe, int i, int chg)
 346 {
 347         for (; chg; chg--, i++)
 348                 if (line_contains_alnum(xe->xdf2.recs[i]->ptr,
 349                                 xe->xdf2.recs[i]->size))
 350                         return 1;
 351         return 0;
 352 }
 353
 354 /*
 355  * This function merges m and m->next, marking everything between those hunks
 356  * as conflicting, too.
 357  */
 358 static void xdl_merge_two_conflicts(xdmerge_t *m)
 359 {
 360         xdmerge_t *next_m = m->next;
 361         m->chg1 = next_m->i1 + next_m->chg1 - m->i1;
 362         m->chg2 = next_m->i2 + next_m->chg2 - m->i2;
 363         m->next = next_m->next;
 364         free(next_m);
 365 }
 366
 367 /*
 368  * If there are less than 3 non-conflicting lines between conflicts,
 369  * it appears simpler -- because it takes up less (or as many) lines --
 370  * if the lines are moved into the conflicts.
 371  */
 372 static int xdl_simplify_non_conflicts(xdfenv_t *xe1, xdmerge_t *m,
 373                                       int simplify_if_no_alnum)
 374 {
 375         int result = 0;
 376
 377         if (!m)
 378                 return result;
 379         for (;;) {
 380                 xdmerge_t *next_m = m->next;
 381                 int begin, end;
 382
 383                 if (!next_m)
 384                         return result;
 385
 386                 begin = m->i1 + m->chg1;
 387                 end = next_m->i1;
 388
 389                 if (m->mode != 0 || next_m->mode != 0 ||
 390                     (end - begin > 3 &&
 391                      (!simplify_if_no_alnum ||
 392                       lines_contain_alnum(xe1, begin, end - begin)))) {
 393                         m = next_m;
 394                 } else {
 395                         result++;
 396                         xdl_merge_two_conflicts(m);
 397                 }
 398         }
 399 }
 400
 401 /*
 402  * level == 0: mark all overlapping changes as conflict
 403  * level == 1: mark overlapping changes as conflict only if not identical
 404  * level == 2: analyze non-identical changes for minimal conflict set
 405  * level == 3: analyze non-identical changes for minimal conflict set, but
 406  *             treat hunks not containing any letter or number as conflicting
 407  *
 408  * returns < 0 on error, == 0 for no conflicts, else number of conflicts
 409  */
 410 static int xdl_do_merge(xdfenv_t *xe1, xdchange_t *xscr1,
 411                 xdfenv_t *xe2, xdchange_t *xscr2,
 412                 xmparam_t const *xmp, mmbuffer_t *result)
 413 {
 414         xdmerge_t *changes, *c;
 415         xpparam_t const *xpp = &xmp->xpp;
 416         const char *const ancestor_name = xmp->ancestor;
 417         const char *const name1 = xmp->file1;
 418         const char *const name2 = xmp->file2;
 419         int i0, i1, i2, chg0, chg1, chg2;
 420         int level = xmp->level;
 421         int style = xmp->style;
 422         int favor = xmp->favor;
 423
 424         if (style == XDL_MERGE_DIFF3) {
 425                 /*
 426                  * "diff3 -m" output does not make sense for anything
 427                  * more aggressive than XDL_MERGE_EAGER.
 428                  */
 429                 if (XDL_MERGE_EAGER < level)
 430                         level = XDL_MERGE_EAGER;
 431         }
 432
 433         c = changes = NULL;
 434
 435         while (xscr1 && xscr2) {
 436                 if (!changes)
 437                         changes = c;
 438                 if (xscr1->i1 + xscr1->chg1 < xscr2->i1) {
 439                         i0 = xscr1->i1;
 440                         i1 = xscr1->i2;
 441                         i2 = xscr2->i2 - xscr2->i1 + xscr1->i1;
 442                         chg0 = xscr1->chg1;
 443                         chg1 = xscr1->chg2;
 444                         chg2 = xscr1->chg1;
 445                         if (xdl_append_merge(&c, 1,
 446                                              i0, chg0, i1, chg1, i2, chg2)) {
 447                                 xdl_cleanup_merge(changes);
 448                                 return -1;
 449                         }
 450                         xscr1 = xscr1->next;
 451                         continue;
 452                 }
 453                 if (xscr2->i1 + xscr2->chg1 < xscr1->i1) {
 454                         i0 = xscr2->i1;
 455                         i1 = xscr1->i2 - xscr1->i1 + xscr2->i1;
 456                         i2 = xscr2->i2;
 457                         chg0 = xscr2->chg1;
 458                         chg1 = xscr2->chg1;
 459                         chg2 = xscr2->chg2;
 460                         if (xdl_append_merge(&c, 2,
 461                                              i0, chg0, i1, chg1, i2, chg2)) {
 462                                 xdl_cleanup_merge(changes);
 463                                 return -1;
 464                         }
 465                         xscr2 = xscr2->next;
 466                         continue;
 467                 }
 468                 if (level == XDL_MERGE_MINIMAL || xscr1->i1 != xscr2->i1 ||
 469                                 xscr1->chg1 != xscr2->chg1 ||
 470                                 xscr1->chg2 != xscr2->chg2 ||
 471                                 xdl_merge_cmp_lines(xe1, xscr1->i2,
 472                                         xe2, xscr2->i2,
 473                                         xscr1->chg2, xpp->flags)) {
 474                         /* conflict */
 475                         int off = xscr1->i1 - xscr2->i1;
 476                         int ffo = off + xscr1->chg1 - xscr2->chg1;
 477
 478                         i0 = xscr1->i1;
 479                         i1 = xscr1->i2;
 480                         i2 = xscr2->i2;
 481                         if (off > 0) {
 482                                 i0 -= off;
 483                                 i1 -= off;
 484                         }
 485                         else
 486                                 i2 += off;
 487                         chg0 = xscr1->i1 + xscr1->chg1 - i0;
 488                         chg1 = xscr1->i2 + xscr1->chg2 - i1;
 489                         chg2 = xscr2->i2 + xscr2->chg2 - i2;
 490                         if (ffo < 0) {
 491                                 chg0 -= ffo;
 492                                 chg1 -= ffo;
 493                         } else
 494                                 chg2 += ffo;
 495                         if (xdl_append_merge(&c, 0,
 496                                              i0, chg0, i1, chg1, i2, chg2)) {
 497                                 xdl_cleanup_merge(changes);
 498                                 return -1;
 499                         }
 500                 }
 501
 502                 i1 = xscr1->i1 + xscr1->chg1;
 503                 i2 = xscr2->i1 + xscr2->chg1;
 504
 505                 if (i1 >= i2)
 506                         xscr2 = xscr2->next;
 507                 if (i2 >= i1)
 508                         xscr1 = xscr1->next;
 509         }
 510         while (xscr1) {
 511                 if (!changes)
 512                         changes = c;
 513                 i0 = xscr1->i1;
 514                 i1 = xscr1->i2;
 515                 i2 = xscr1->i1 + xe2->xdf2.nrec - xe2->xdf1.nrec;
 516                 chg0 = xscr1->chg1;
 517                 chg1 = xscr1->chg2;
 518                 chg2 = xscr1->chg1;
 519                 if (xdl_append_merge(&c, 1,
 520                                      i0, chg0, i1, chg1, i2, chg2)) {
 521                         xdl_cleanup_merge(changes);
 522                         return -1;
 523                 }
 524                 xscr1 = xscr1->next;
 525         }
 526         while (xscr2) {
 527                 if (!changes)
 528                         changes = c;
 529                 i0 = xscr2->i1;
 530                 i1 = xscr2->i1 + xe1->xdf2.nrec - xe1->xdf1.nrec;
 531                 i2 = xscr2->i2;
 532                 chg0 = xscr2->chg1;
 533                 chg1 = xscr2->chg1;
 534                 chg2 = xscr2->chg2;
 535                 if (xdl_append_merge(&c, 2,
 536                                      i0, chg0, i1, chg1, i2, chg2)) {
 537                         xdl_cleanup_merge(changes);
 538                         return -1;
 539                 }
 540                 xscr2 = xscr2->next;
 541         }
 542         if (!changes)
 543                 changes = c;
 544         /* refine conflicts */
 545         if (XDL_MERGE_ZEALOUS <= level &&
 546             (xdl_refine_conflicts(xe1, xe2, changes, xpp) < 0 ||
 547              xdl_simplify_non_conflicts(xe1, changes,
 548                                         XDL_MERGE_ZEALOUS < level) < 0)) {
 549                 xdl_cleanup_merge(changes);
 550                 return -1;
 551         }
 552         /* output */
 553         if (result) {
 554                 int marker_size = xmp->marker_size;
 555                 int size = xdl_fill_merge_buffer(xe1, name1, xe2, name2,
 556                                                  ancestor_name,
 557                                                  favor, changes, NULL, style,
 558                                                  marker_size);
 559                 result->ptr = xdl_malloc(size);
 560                 if (!result->ptr) {
 561                         xdl_cleanup_merge(changes);
 562                         return -1;
 563                 }
 564                 result->size = size;
 565                 xdl_fill_merge_buffer(xe1, name1, xe2, name2,
 566                                       ancestor_name, favor, changes,
 567                                       result->ptr, style, marker_size);
 568         }
 569         return xdl_cleanup_merge(changes);
 570 }
 571
 572 int xdl_merge(mmfile_t *orig, mmfile_t *mf1, mmfile_t *mf2,
 573                 xmparam_t const *xmp, mmbuffer_t *result)
 574 {
 575         xdchange_t *xscr1, *xscr2;
 576         xdfenv_t xe1, xe2;
 577         int status;
 578         xpparam_t const *xpp = &xmp->xpp;
 579
 580         result->ptr = NULL;
 581         result->size = 0;
 582
 583         if (xdl_do_diff(orig, mf1, xpp, &xe1) < 0 ||
 584                         xdl_do_diff(orig, mf2, xpp, &xe2) < 0) {
 585                 return -1;
 586         }
 587         if (xdl_change_compact(&xe1.xdf1, &xe1.xdf2, xpp->flags) < 0 ||
 588             xdl_change_compact(&xe1.xdf2, &xe1.xdf1, xpp->flags) < 0 ||
 589             xdl_build_script(&xe1, &xscr1) < 0) {
 590                 xdl_free_env(&xe1);
 591                 return -1;
 592         }
 593         if (xdl_change_compact(&xe2.xdf1, &xe2.xdf2, xpp->flags) < 0 ||
 594             xdl_change_compact(&xe2.xdf2, &xe2.xdf1, xpp->flags) < 0 ||
 595             xdl_build_script(&xe2, &xscr2) < 0) {
 596                 xdl_free_env(&xe2);
 597                 return -1;
 598         }
 599         status = 0;
 600         if (!xscr1) {
 601                 result->ptr = xdl_malloc(mf2->size);
 602                 memcpy(result->ptr, mf2->ptr, mf2->size);
 603                 result->size = mf2->size;
 604         } else if (!xscr2) {
 605                 result->ptr = xdl_malloc(mf1->size);
 606                 memcpy(result->ptr, mf1->ptr, mf1->size);
 607                 result->size = mf1->size;
 608         } else {
 609                 status = xdl_do_merge(&xe1, xscr1,
 610                                       &xe2, xscr2,
 611                                       xmp, result);
 612         }
 613         xdl_free_script(xscr1);
 614         xdl_free_script(xscr2);
 615
 616         xdl_free_env(&xe1);
 617         xdl_free_env(&xe2);
 618
 619         return status;
 620 }